1. Field of the Invention
This invention relates to new and improved apparatus and method for exchanging substances between the same or different substance carrier and substance recovery fluids, by separation of the substance from the former and recovery by the latter, in predetermined substance carrier/substance recovery fluid volumetric ratios; particularly as applied to substances which are constituted by analytes, and carrier and recovery fluids which are constituted by solvents.
2. Description of the prior art.
Although a variety of prior art apparatus and methods are known for the purposes disclosed herein, none are known to be configured and operable in the manners of those of this invention, or to provide the combination of particularly significant advantages as are provided by the latter. Most relevantly, the solvent concentrator disclosed in FIG. 3 of paper by D. Keuhl, et al., entitled "Novel Approaches To Interfacing A High Performance Liquid Chromatograph With A Fourier Transform Infrared Spectrometer," Journal of Chromatographic Science, Volume 17, August 1979, pages 471-476, although operable to the same general purposes as those of this invention insofar as substance concentration per se is concerned, is nonetheless quite remote therefrom in lacking the capability to deposit the substance of interest in a narrow compressed band at a predeterminable location in the light pipe concentrating tube because the substance must be sprayed into the concentrating tube. Further, although substance recovery in small recovery fluid volumes might be possible in this prior art concentrator, the same would require the use of very small concentrator tubes with attendant significant reduction in tube surface area and resultant very low substance concentration rates.
Also relevant, but to a somewhat lesser degree, are the basic "purge and trap" substance concentration apparatus and methods of the prior art as disclosed for example in U.S. Pat. No. 4,180,389, and embodied for example in the CDS GC Sample Concentrators as manufactured by Chemical Data Systems, Inc. of Chicago, Ill., the Trace Organics Concentrators as manufactured by Valco Instruments Systems, Inc. of Houston, Tex., and the Trace Enrichment Systems as manufactured by Bioanalytical Systems, Inc. of Lafayette, Ind.; which, although operable to the same general purposes as the apparatus and method of this invention insofar as substance concentration per se is concerned, are nonetheless quite remote therefrom in requiring desorption on one or more adsorbent traps, and repeated backflushing and/or reverse trap heating or like procedures to, in any event, significantly limit the range of applications thereof.
Of limited relevance are the zone refining techniques of the prior art, as disclosed for example in paper of V.L. Poland entitled "Zone Refining, What it can do for you?" Intek (in-house publication of Abbott Laboratories, Chicago, Ill.) Vol. 6, Number 11, Nov. 1970, pages 1-3; which, although capable of ultimately effecting very high substance concentrations, are even more remote from the apparatus and method of this invention. More specifically, these techniques separate by relating melting points as a function of the relative compositions of a solid and molten state, rather than as a function of relative vapor pressures; and require, for example, laborious repeated passes of the carrier of the substance to be concentrated relative to heating means to effect the requisite plurality of concentrating zone passes and the desired high degree of substance concentration.
In addition, and with the exception of the CDS Concentrators, the relevant prior art apparatus and methods under discussion will generally be found to be configured for operation on what is essentially a batch basis and thus not particularly, if at all, adaptable as a practical matter for operation attendant the automated analysis of a series of samples on a continuous flow successive basis in accordance with contemporary automated sample analysis procedures and devices.